The earliest mention (citation needed) that there is a rabbit on the moon appears in the Chu Ci, a Western Han anthology of Chinese poems from the Warring States period, which notes that along with a toad, there is a rabbit on the moon who constantly pounds herbs for the immortals. This notion is supported by later texts, including the Imperial Readings of the Taiping Era encyclopedia of the Song Dynasty. Han Dynasty poets call the rabbit on the moon the Jade Rabbit or the Gold Rabbit (金兔), and these phrases were often used in place of the word for the moon. A famous poet of the Tang Dynasty period, Li Bai, relates how: "The rabbit in the moon pounds the medicine in vain" in his poem "The Old Dust."